ZIP archive of 1.46 MB for the original Apple iPhone, commonly called the iPhone 2G. The name states only the model, so the precise contents should be checked after extraction; such packages typically carry a schematic or board layout drawings. For this first-generation phone they help identify components, follow the power and charging paths and locate test points when restoring units that will not power on. Compare board markings with the document before replacing parts, as this model predates the later 3G board design.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.